Abstract
The present study was designed to investigate the efficacy of an aqueous calyx extract of
Hibiscus sabdariffa (HS) in two forms of experimental hypertension: salt-induced and
l-NAME (
N
ω-
l-arginine methyl ester)-induced and in normotensive controls. The blood pressure and heart rate fell dose-dependently in both the hypertensive and normotensive rats after intravenous injection of 1–125 mg/kg of HS, suggesting that HS possesses anti-hypertensive, hypotensive and negative chronotropic effects. The fall in mean arterial pressure was significantly pronounced in the hypertensive rats (salt-induced: 94.4
±
8.6 mm Hg;
l-NAME-induced: 136.5
±10.3 mm Hg) than in the normotensive controls (50.2
±
5.1 mm Hg;
P
<
0.05).